In the perfume industry there is a fundamental need for new fragrance substances. With new fragrance substances the intention is to produce novel effects, to create new fashion trends and hence to satisfy the growing consumer demand for new, modern fragrance notes. Fragrances of this type should inherently be as original as possible and possess a high sensorial intensity and fullness. Even in low dosages they should allow sensorially perceptible, striking fragrance effects to be achieved.
Fragrance substances which are capable of imparting a near-natural scent to perfume compositions are particularly valuable here. Such near-naturalness can be achieved by the use of natural extracts such as flower extracts and essential oils, for example. However, because of the laborious manner in which they are obtained, natural products such as natural extracts are expensive, not available in unlimited quantities and subject to considerable fluctuations in quality. There is accordingly a need for synthesisable chemical substances and blends having a fragrance that is as near-natural as possible.
Mixtures of isomers of 3,3,5-trimethylcyclohexyl ester are known to be fragrance substances. For instance, S. Arctander, Perfume and Flavor Materials, Vol. I and II, Montclair, N.J., 1969, self-published, Monograph 3003, mentions 3,3,5-trimethylcyclohexyl acetate as exhibiting the following fragrance characteristics: weak, sweetly minty, herbal. A distinction is not made in this publication between the fragrance characteristics of cis- and trans-3,3,5-trimethylcyclohexyl acetate.
In Tluszcze, Srodki Piorace, Kosmetyki 19, 516-20 (1975) the olfactory characteristics of the formate, acetate and propionate of 3,3,5-trimethylcyclohexanol having a content of trans isomers of more than 95% are described. According to this publication, the formate smells of camphor, cineol, iris and sandalwood. The acetate apparently smells of woodland herbs with a thuja, lavender and spruce-like scent, this scent being described as being of interest and advantage to the perfume industry. The propionate supposedly has a mango-like aroma with a slight honey note and an iris-like background.
JP 01 056798 describes perfume oils for use in detergents containing bleach. 3,5,5-Trimethylcyclohexyl isobutyrate is listed as one of the possible perfume oils. Once again, no distinction is made between the cis and trans isomers.
WO 01/43784 describes the substances 3,3,5-trimethylcyclohexyl acetate, 3,3,5-trimethylcyclohexyl propionate, 3,3,5-trimethylcyclohexyl crotonate and 3,3,5-trimethylcyclohexyl butyrate and their use to neutralise unpleasant odours. The cited substances themselves apparently have only a very slight characteristic odour. In the olfactory assessment, no distinction is made here between the cis and trans isomers of these substances.
The object of the present invention was therefore to provide further fragrance substances which are as original as possible, have a high sensorial intensity and fullness and impart as near-natural a fragrance as possible to perfume compositions. In addition the fragrance substances should be obtainable with as consistent a quality as possible and by simple means.
The search for suitable fragrance substances, which led to the present invention, was made more difficult by the following facts:                The mechanisms of fragrance perception are not adequately known        The correlations between the special fragrance perception on the one hand and the chemical structure of the associated fragrance substance on the other have not been sufficiently researched        There is no correlation between the fragrance characteristics and the toxicological safety of a substance        Even minor changes to the structural make-up of a known fragrance substance frequently bring about major changes to the sensorial properties and reduce its compatibility for the human organism.        
The success of the search for suitable fragrance substances is therefore highly dependent on the intuition of the person engaged in the search.